From db1176ce66cf276b45ac3b90ea6b5ce62de56be7 Mon Sep 17 00:00:00 2001
From: Roman Lebedev <lebedev.ri@gmail.com>
Date: Sat, 5 Feb 2022 02:29:28 +0300
Subject: Revert "[SimplifyCFG] `markAliveBlocks()`: recognize that normal dest
 of `invoke`d `noreturn` function is `unreachable`"

The normal destination may have other uses.

This reverts commit 598833c987593ce192fa827f162cae8c867c9d43.
---
 llvm/lib/Transforms/Utils/Local.cpp | 39 +++++++++++++------------------------
 1 file changed, 13 insertions(+), 26 deletions(-)

(limited to 'llvm/lib/Transforms/Utils/Local.cpp')

diff --git a/llvm/lib/Transforms/Utils/Local.cpp b/llvm/lib/Transforms/Utils/Local.cpp
index 58eb7d4..9a10535 100644
--- a/llvm/lib/Transforms/Utils/Local.cpp
+++ b/llvm/lib/Transforms/Utils/Local.cpp
@@ -2349,32 +2349,19 @@ static bool markAliveBlocks(Function &F,
           isa<UndefValue>(Callee)) {
         changeToUnreachable(II, false, DTU);
         Changed = true;
-      } else {
-        if (II->doesNotReturn()) {
-          // If we found an invoke of a no-return function,
-          // insert an unreachable instruction after it (on the normal dest).
-          // Make sure there isn't *already* one there though.
-          Instruction *FirstNormalInst = &II->getNormalDest()->front();
-          if (!isa<UnreachableInst>(FirstNormalInst)) {
-            // Don't insert a call to llvm.trap right before the unreachable.
-            changeToUnreachable(FirstNormalInst, false, DTU);
-            Changed = true;
-          }
-        }
-        if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(&F)) {
-          if (II->use_empty() && II->onlyReadsMemory()) {
-            // jump to the normal destination branch.
-            BasicBlock *NormalDestBB = II->getNormalDest();
-            BasicBlock *UnwindDestBB = II->getUnwindDest();
-            BranchInst::Create(NormalDestBB, II);
-            UnwindDestBB->removePredecessor(II->getParent());
-            II->eraseFromParent();
-            if (DTU)
-              DTU->applyUpdates({{DominatorTree::Delete, BB, UnwindDestBB}});
-          } else
-            changeToCall(II, DTU);
-          Changed = true;
-        }
+      } else if (II->doesNotThrow() && canSimplifyInvokeNoUnwind(&F)) {
+        if (II->use_empty() && II->onlyReadsMemory()) {
+          // jump to the normal destination branch.
+          BasicBlock *NormalDestBB = II->getNormalDest();
+          BasicBlock *UnwindDestBB = II->getUnwindDest();
+          BranchInst::Create(NormalDestBB, II);
+          UnwindDestBB->removePredecessor(II->getParent());
+          II->eraseFromParent();
+          if (DTU)
+            DTU->applyUpdates({{DominatorTree::Delete, BB, UnwindDestBB}});
+        } else
+          changeToCall(II, DTU);
+        Changed = true;
       }
     } else if (auto *CatchSwitch = dyn_cast<CatchSwitchInst>(Terminator)) {
       // Remove catchpads which cannot be reached.
-- 
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